1. Field
Example embodiments relate to a draw solute for forward osmosis, a forward osmosis water treatment device using the same, and a forward osmosis method for water treatment.
2. Description of the Related Art
In general, desalination through reverse osmosis is commonly known in the field of water treatment. Osmosis (i.e., forward osmosis) refers to a phenomenon in which water in a portion of lower concentration moves to a solution of higher concentration. On the other hand, reverse osmosis desalination is a process of artificially adding a relatively high pressure to move water in the opposite direction, thereby producing fresh water. Since reverse osmosis requires a relatively high pressure, it has higher energy consumption. Recently, to increase energy efficiency, forward osmosis that uses the principle of osmotic pressure has been suggested, and a solute for the osmosis draw solution including ammonium bicarbonate, sulfur dioxide, aliphatic alcohols, aluminum sulfate, glucose, fructose, potassium nitrate, and the like have been used. Among them, an ammonium bicarbonate draw solution is most commonly known, and may be decomposed into ammonia and carbon dioxide and separated at a temperature of about 60° C. after forward osmosis. Further, newly suggested draw solution materials include magnetic nanoparticles having a hydrophilic peptide attached thereto (separated by a magnetic field), a polymer electrolyte such as a dendrimer (separated by a UF or NF membrane), and the like.
In the case of ammonium bicarbonate, it should be heated to about 60° C. or more so as to be vaporized, thus requiring higher energy consumption, and since complete removal of ammonia is practically difficult, it is impossible to use it as drinking water due to the odor of ammonia. In the case of the magnetic nanoparticles, it is difficult to redisperse magnetic particles that are separated and agglomerated by a magnetic field. It is also difficult to completely remove the nanoparticles, and thus toxicity of the nanoparticles should be considered. Polymer ion (dendrimer, protein, etc.) technology requires a nanofiltration or ultrafiltration membrane filter due to the RH size of the polymer of several to tens of nanometers, and it is also difficult to redisperse the agglomerated polymer after filtering.